The issue of disposability of products is a great concern to the nonwovens industry. Landfills, incineration, multiple sewage treatment and residential septic systems are among the common choices for nonwoven product disposal today. Products targeted for the latter disposal routes via residential and commercial toilets are termed flushable. Current flushable products have limitations. Dry products, such as bathroom tissue, have been designed with minimal wet strength so that the tissue can disintegrate under the agitation in the plumbing systems. They are not designed for applications where water will be encountered in use. Flushable wet wipes have high wet strengths and do not lose their strength upon disposal. These products remain intact and identifiable in the disposal system.
Wet-packaged skin cleansing and refreshing tissues are well known commercially, generally referred to as towelettes, wet wipes, fem wipes and the like. These may comprise an absorbent sheet made of paper, prepared or treated to impart wet strength thereto, having the dimensions of the usual washcloth and packaged wet in folded condition individually in impervious envelopes or in multiples in closed containers. The liquid employed in premoistening the sheet is generally an aqueous alcoholic solution which may further contain a surface active detergent and a humectant and, in some instances, also a scenting agent. Instead of individual packaging of such moist sheets, they are often marketed in reclosable containers having any desired convenient number of such folded sheets.
U.S. Pat. Nos. 4,258,849 and 4,343,403 disclose pre-moistened towelettes which are flushable. These towelettes incorporate a polyvinyl alcohol (PVOH) or PVOH stabilized emulsion as a binder, respectively, and an aqueous pre-moistening lotion which contains salts (especially boric acid) that insolubilize the PVOH to impart good strength and integrity. Relatively high salt concentrations are required to impart good strength. For example, useful performance is not achieved until at least 3% boric acid is used. All other useful insolubilizing salts for PVOH need to be used at much higher concentrations to achieve the same effect. Wipes prepared with these types of binders rapidly disintegrate by reduction in salt concentration and solubilization of the PVOH based binder.
However, the salt containing formulations cannot be used in some applications such as cleaning wipes or some personal care wipes where lotion residues due to the salts are not acceptable. These salts are not volatile and will deposit as streaks or white powdery residue on the surface as the lotion evaporates.
There is a desire in the nonwovens industry to make cleaning wipe products which do not leave residues such as bathroom or hospital disinfecting wipes which can also be disposed of in the toilet after use.
There is a general need to supply non-water based medical, cosmetic or personal care formulations by means of a pre-moistened towelette. These formulations may come in contact with body fluids, which for sanitary reasons, may then be disposed of in the toilet. These products to date have been applied to small towelettes since they are incapable of disintegration upon disposal in water. Large size or high number of these products would result in clogging of the plumbing systems. Also, pre-moistened towelettes manufactured today are not generally recyclable or easily degraded in the environment due to their use of non-water redispersible binders such as vinyl acetate/ethylene/N-methyolacrylamide (VAE/NMA) copolymers.
This problem of salt residue has been partially addressed in U.S. Pat. No. 4,309,469. The use of multi-component binder formulations and multi-component lotion salt compositions are described in which total salt concentration is reduced to 1%. This level is still too high to solve the problem. In general, this issue has not been addressed since the PVOH/salt technology has not been targeted for surface cleaning applications. The market for pre-moistened wipes is rapidly growing and new products containing specific lotion cleaning fluids have just entered the market. These current products do not disintegrate in water and are not designed to be disposed in the toilet.